Motorola BD50 F3 Replacement Battery 3.7V 750mAh

Motorola F3 / EM325 Series — 3.7V Li-ion Replacement Battery (BD50)

This is a 3.7V, 750mAh Li-ion cell that replaces the OEM BD50 battery in the Motorola F3, F3C, EM325, and EM25 handsets. It fits the same slot and uses the same three-contact connector as the original. Capacity matches the factory spec at 2.78Wh.

• F3 and EM series compatibility: The F3, F3C, EM325, and EM25 all share the same battery bay dimensions and contact layout. Motorola used the BD50 cell across this range, so one part number covers all four models without modification.
• Bench tested on actual hardware: We cycled this cell in an F3 handset and confirmed the BMS accepted the charge handshake on the first connection. Charge current stepped up correctly through CC and CV phases with no false termination.
• Fuel gauge recalibration on first cycle: On first use after installation, run one complete discharge before recharging. The F3's fuel gauge IC holds the old cell's discharge curve in memory. A full cycle overwrites it and stops the percentage jumping around during the first few days of use.

Sudden shutdown at 20–30% on the Motorola F3

The F3's processor and GSM radio draw a sharp current spike during a call or network search. If the cell's internal resistance is elevated — whether from age or a storage-depleted new cell — voltage sags below the BMS cutoff threshold under that load, and the phone shuts off even though the fuel gauge still shows charge remaining. The fix is a full conditioning cycle: discharge the phone to shutdown, then charge uninterrupted to 100%. This resets the coulomb counter and lets the BMS learn the actual low-voltage floor of the new cell.

Phone won't power on after the battery sat in storage

Li-ion cells self-discharge in storage. If this battery shipped at a low state of charge and sat for several weeks before installation, cell voltage may have dropped below 2.5V — the threshold where the BMS locks out to prevent damage. The F3 will show nothing when you press the power button. Connect the phone to a wall charger, not a USB port, and leave it for 20–30 minutes before attempting to power on. Wall adapters supply enough current to nudge the BMS out of lockout; USB ports on laptops often cannot.